Experiments are designed to establish the Mongolian gerbil as an important natural model for the study of seizure disorders and to demonstrate the unique contributions this model can make. The experiments are divided into three phases. Experiments in Phase 1 attempt to characterize the model by investigating differences in seizure prone and nonseizure prone gerbils with respect to activity, emotionality, and learning. Experiments in Phase 2 will investigate the effects of ontogenetic manipulations on later seizure activity. These will include effects of cross fostering, isolation, and environmental enrichment. Phase 3 will investigate the seizure's refractory period to determine whether the gerbils are truly refractory during this time or whether they do not undergo seizures because they have become habituated to the seizure test.